Great question, Cyndi. The most successful way I’ve found to increase endurance (without pain) is to do the following:

Set aside one run per week as your long run. Most runners do this on the weekend, but it can be run on any day.

Overall pace should be about 4-5 minutes per mile slower than you run in the 5-K. If you don’t have a 5-K time, then slow down so that you never huff and puff—even at the end of the run. (It will only help your recovery if you run slower than this pace. When in doubt, slow down.)

Increase your long run by half a mile to a mile on each long one. One week you could increase, and the next week you could cut the distance in half.

Insert walk breaks from the beginning. This will significantly reduce fatigue and allow your legs to be strong to the end. Walk break ratios are tied to the pace per mile and can be found on my web site.

Olympian Jeff Galloway has helped thousands of runners achieve their goals through his e-coaching, Galloway Programs across the U.S., retreats, half day running schools, books, and individual consultations. For more information on this topic or Jeff's programs, visit JeffGalloway.com.